President Barack Obama meets with Saudi King Abdullah at Rawdat Khuraim, Saudi Arabia, on Friday.

RIYADH, Saudi Arabia — The United States is considering allowing shipments of portable air defense systems to Syrian rebels, a U.S. official said Friday, as President Barack Obama sought to reassure Saudi Arabia’s king that the U.S. is not taking too soft a stance in Syria and other Mideast conflicts.

The president and King Abdullah met for more than two hours at the aging monarch’s desert oasis outside the capital city of Riyadh. Obama advisers said the two leaders spoke frankly about their differences on key issues, with the president assuring the king that he remains committed to the Gulf region’s security.

Saudi officials have grown particularly concerned about what they see as Obama’s tepid response to the Syrian civil war and have pressed the U.S. to allow them to play a direct role in sending the rebels the air defense systems commonly known as manpads. While administration officials have previously ruled out that option, a senior official said it was being considered, in part because the U.S. has been able to develop deeper relationships with the Syrian opposition over the past year.

The official said no final decision had been made and the president might ultimately decide against the proposal. One of Obama’s top concerns continues to be whether the weaponry would fall into the wrong hands, according to the official, who was not authorized to discuss internal deliberations by name and commented only on condition of anonymity. The official cast the approach as less of a sudden change in position and more an indication of how the U.S. has viewed the issue for some time.

A second senior official said there had been no change in the U.S. position on manpads, but did not specifically rule out the notion that the option was under consideration.

Manpads are compact missile launchers with the range and explosive power to attack low-flying planes and helicopters. U.S. officials have estimated the Syrian government has thousands.

The decades-long alliance between the U.S. and Saudi Arabia has been a pillar of security arrangements in the Middle East. But as U.S. troops have pulled out of Iraq and Afghanistan, the kingdom’s royal family has become increasingly anxious about Obama’s positioning in the region.

Tensions reached a high point last fall after Obama decided against launching a military strike on Syria, choosing instead to back a plan to strip Syrian President Bashar Assad of his chemical weapon stockpiles. U.S. officials say the relationship has improved since then, with both sides making an effort to more closely coordinate their efforts to halt the Syrian conflict.

“We are in a better place today than we were seven months ago,” said Ben Rhodes, Obama’s deputy national security adviser.

Beyond Syria, one of the king’s biggest concerns has been the U.S.-led nuclear negotiations with Iran. The Saudis fear Iran’s nuclear program, object to Iran’s backing of the Assad government and see Tehran as having designs on oil fields in Saudi Arabia and Bahrain.

Officials said the nuclear negotiations were a primary topic of Friday’s meeting, with Obama assuring the king that the U.S. was not glossing over Tehran’s other provocations in order to get a final deal.

The president arrived in Riyadh Friday evening, then quickly boarded the presidential helicopter for a 30-minute flight to the king’s desert camp. Obama walked through a row of military guards to an ornate room featuring a massive crystal chandelier and took a seat next to the king, who appeared to be breathing with the assistance of an oxygen tank.